Master Python’s hashlib: From MD5 to SHA‑512 and Custom Key Encryption

Introduction

In Python we often need to compute cryptographic hashes such as MD5 and SHA‑1. The hashlib module provides a convenient way to generate these digests. It works on binary data, so strings must be encoded before hashing.

Basic Usage

import hashlib
string = '任性的90后boy'
# Using encode
a = hashlib.sha1()
a.update(string.encode('utf-8'))
print('sha1 with encode:', a.hexdigest())
# Using bytes directly
a = hashlib.sha1()
a.update(bytes(string, encoding='utf-8'))
print('sha1 with bytes:', a.hexdigest())

The following two attributes list all available hash algorithms:

import hashlib
print(hashlib.algorithms_available)
print(hashlib.algorithms_guaranteed)

1. MD5

MD5 (Message‑Digest Algorithm 5) produces a 128‑bit hash value. It is fast, widely supported, and commonly used for checksums, though it is not collision‑resistant for security‑critical purposes.

import hashlib
string = '任性的90后boy'
md5 = hashlib.md5()
md5.update(string.encode('utf-8'))
print('MD5 digest (hex):', md5.hexdigest())
print('MD5 digest (bytes):', md5.digest())

2. SHA‑1

SHA‑1 generates a 160‑bit hash represented as a 40‑character hexadecimal string.

import hashlib
string = '任性的90后boy'
sha1 = hashlib.sha1()
sha1.update(string.encode('utf-8'))
print('SHA‑1 result:', sha1.hexdigest())

3. SHA‑224

import hashlib
string = '任性的90后boy'
sha224 = hashlib.sha224()
sha224.update(string.encode('utf-8'))
print('SHA‑224 result:', sha224.hexdigest())

4. SHA‑256

import hashlib
string = '任性的90后boy'
sha256 = hashlib.sha256()
sha256.update(string.encode('utf-8'))
print('SHA‑256 result:', sha256.hexdigest())

5. SHA‑384

import hashlib
string = '任性的90后boy'
sha384 = hashlib.sha384()
sha384.update(string.encode('utf-8'))
print('SHA‑384 result:', sha384.hexdigest())

6. SHA‑512

import hashlib
string = '任性的90后boy'
sha512 = hashlib.sha512()
sha512.update(string.encode('utf-8'))
print('SHA‑512 result:', sha512.hexdigest())

7. Simple Key‑Based Encryption

Standard hash functions are vulnerable to rainbow‑table attacks. Adding a custom key (salt) before hashing can improve security.

# Simple MD5 with a custom key
import hashlib
md5 = hashlib.md5()
md5.update('md5'.encode('utf-8'))
print('Plain MD5:', md5.hexdigest())

md5_key = hashlib.md5(b'md512')
md5_key.update('md5_key'.encode('utf-8'))
print('MD5 with key:', md5_key.hexdigest())

Conclusion

We have covered the most commonly used hash algorithms in Python’s hashlib module, demonstrated how to compute their digests, and introduced a basic key‑based approach for enhancing hash security.